In the average player's mind, Guild Halls are often a place to chat with guildmates and have guild meetings, etc., and that's something I agree with. But everything can be spiced up a bit, so let's go through my list of suggestions for the Guild Halls of Spiral Knights.
Guild Sparring Chambers:
A basic place for guild members to practice PvP related things, simply learn how the games work. There are no payments or rewards for/from matches in the Guild Sparring Chambers. Requires F5 West Wing upgrade.
Price: 50m Crowns
Guild Training Hall Upgrades: